Finally got to wake up my 83 300SD a little bit and hopefully did it some good.

It was downright scary pulling in to traffic. I'm sure people behind me were pretty much going "WTF?" almost every day. Curiously, my parts car was much quicker and it's a piece of junk. So I knew I could do better.

I resisted the urge to just start cranking on the ALDA screw. I figured I'd save that til last and try to make more "important to the health of the engine" changes first.

I started with the banjo bolts on the ALDA lines. the one on the manifold was 100% clogged. Oddly, this didn't make a difference. It almost felt worse. Maybe just because I was expecting better performance and didn't get it. I almost wonder if the line is crudded up. If so, maybe it will blow into the bolt and I'll clean that again in a few months.

Then I did a two can diesel purge. The results of the second can didn't look as bad as the first can, but here's what I was left with.



The biggest thing this did was smooth the idle. It almost didn't sound like a diesel any more! There MAY have been an almost imperceptible change off the line. I could never make up my mind.

So then I ripped into the virgin ALDA, starting by ripping off the cap. How do people get those to look so clean? Can you remove it all the way? Mine is all jagged.

I wound up turning it 1 1/2 turns with no smoke. I quit there because I didn't have a helper and could only see what smoke came up to the rear window level. This was the thing that really clinched it as far as pulling in to traffic. I feel so much safer now.

There's almost a two-stage effect when I accelerate from a dead stop - like after a second, a little more power kicks in. It's not the turbo or a gear shift, but it just seems like an extra little "bit" of power after about a second. Does anyone know what I'm describing?

Anyway - sorry for the long post. I'm no mechanic, so I'm all proud of myself. I used to play around with Jeeps like 20 years ago, but just getting back into hobby cars and never had a diesel.

So! What's next? I'm thinking EGR delete and figure out my tach problem so I can test the boost, which I already have the stuff for - just didn't know it was tach-dependent.

Try pulling a vacuum on the ALDA. If it can't hold vacuum, it won't hold pressure either. The seals in it can dry out, fail, and leak and will cause a low-enrichment condition. With a properly functioning ALDA, you shouldn't get the sudden surge as the turbo builds, it should be smooth and civilized.

I have a capped ALDA on my SDL and after resealing it with new O-rings, you can't even tell where the enrichment begins unless you have the pedal to the floor. Makes it MUCH nicer around town to drive since you don't have to rev the nuts off it to keep up with traffic anymore.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

Congrats on your venture into maintence and modding.

Valve adjustment, drive it like you stole it, and valve adjustment again in 500 miles.
Change all fluids and filters.
Compression check, after valve adjstment #2, to see where you are as far as engine health goes.

Flaky tach usually due to poor tach amplifier solder joints or poor contact at the female pins on the "diagnostic port" connector undr the tach amplifier.

Diseasel300 has excellent advice on checking the health of the ALDA (I plan to test my cars tomorrow when I find my MityVac).

You can read boost directly from the ALDA with a mechanical boost gauge (or the pressure side of a MityVac also works).
First just swap out the stock banjo bolt on the ALDA with one from a 85 OM617A that has the
nipple fitting - (for the hose to the 85 vacuum amplifier...aka "blue flyimg saucer").
Then conncet your boost gauge/Mityvac to the nipple with a vacuum hose and you are good to go.

I have this mod for the mechanical boost gauge setup on my 76 W116 300SD (thanks to mach4).

EGR delete - couple of methods
1) BB in EGR vacuum line
2) Soda can gasket between EGR valve and exhaust manifold (on my 83 W126 300SD)
3) ROLLGUY's EGR delete kit (or similar)
4) Cut and crimp close the EGR tube
5) Non-EGR intake and exhaust manifolds from a 78-79 W116 300SD

PM me if you'd like the non-EGR manifolds.
I have sold many sets to forum members here and at superturbodiesel.com.
I even have a spare W115 longrunner intake available in addition to the non-EGR W116 manifolds.

__________________
78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

Thanks for the replies. I'm afraid I don't understand "pulling a vacuum on the ALDA".

The valve adjustment and all fluids have already been done. I took the car in for a PPI and had that done before I even took possession. I'll maintain the fluids, but figured I'd get it with a "fresh start" and track the records from here on out.

I've seen probably 20 times a reference to people fixing or at least temporarly getting their tach to work by "stuffing something in" the amplifier - even a cigarette butt mentioned specifically. But never seen a picture or more detailed description of where one should "stuff" something. My tach either doesn't do anything, works fine, flies all around, or does crazy stuff like read 6K at idle. Mercedes Source suggest the line to the amplifier could be the culprit as well.

I'll keep an eye out for an '85 in the junk yards.

I'm planning on using an EGR delete kit just to clean things up and give more room.

Thanks again!

With the Engine cold and off hold the throttle lever on the Fuel Injection Pump and have one slowly step on the Accelerator Pedal. Watch the linkages and see how much slop is in them.

If there is a lot of slop in the linkages it could be were in the pivot or rubber on the Fire Wall or the linkages are out of adjustment.

There is specific lengths for the linkages in the Factory Service Manual.

If someone has not mentioned the valve adjustment needs to be done and there is timing chain stretch (which effects camshaft timing) and then the Fuel Injection Pump timing.

__________________
84 300D, 82 Volvo 244Gl Diesel

The ALDA is supposed to be a sealed device. It has an aneroid capsule in it that compresses when the boost in the manifold builds, the result being that the plunger is raised in the injection pump.

If the ALDA leaks, you will not get the fuel enrichment you expect because all the boost pressure that is SUPPOSED to be collapsing the aneroid capsules is escaping into the engine sump through the leaking seals. The result is low power due to low turbo boost from low enrichment.

If you have a hand vacuum pump, you can test the airtightness of your ALDA by attaching it to the ALDA and attempting to pull vacuum on it. If you can pull vacuum and it will hold vacuum, you know that it is airtight. I'd bet dollars to donuts that it leaks like a sieve. I have 3 ALDAs and all 3 of them leaked. One of them much worse than the others.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

Screwing with the alda is the current dog trick, but the alda itself rarely causes a problem. Go back to the Alda line. I'm not familiar with this version, but on most it doesn't go directly to the Alda, but is controlled by a vacuum switchover relay. Make sure the entire airway from manifold to Alda is clear. If you can hook up a pressure gauge to manifold port, measure how much boost your are getting.

- on the back of your intake manifold, there is a hollow bolt that comes from the ALDA. 13mm IIRC - remove it - watch for washers falling - and make sure it is clear and not sooted up


- valve adjustment
- check the chain timing - PeachPartsWiki: Measuring Timing Chain Stretch
- fuel filters

these cars will run great with modern traffic if they are tuned up correctly. i've never had to mess with the ALDA on any of my vehicles.

learn how to check boost pressure to the intake manifold - you need to make sure you aren't harming the engine with too much boost by turning up the ALDA.

good luck - and enjoy!

__________________
-------------------------------
'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

Thanks for all the replies.

I think I need to get a vacuum pump next. I also need to diagnose my door locks, and I can use it to bleed brakes all for $40. That sounds doable.

As far as the suggestion to get a line from an 85 - my 83 terminates into a rubber hose section at the "switchover valve?". could I just do it from there?

I think I'm gong to revisit the manifold hose - maybe let it go a few rounds in the ultrasonic cleaner. The performance gain was so disappointing for how much crud I saw, I'm not convinced that hose isn't blocked.

That would also work, you just need the right size tee and some vacuum hose.

The banjo bolt with the nipple from an '85 is less likely to leak over the long term on a permanent installation.

__________________
78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022